This invention relates to a housing for a memory module. In particular, it relates to a housing for a data card, which may, for example, form part of a radiotelephone housing.
Memory modules such as data cards are known, for example, in cellular radiotelephones, which may be removably inserted into the telephone. A data card may be a passive memory card (i.e. essentially a ROM), or an active processor card (i.e. capable of processing information internally within the card). Data, such as identity information, is read from the inserted card and used in the subsequent operation of the telephone. The data card may be, for example, a "smart card" which is similar in size to a conventional plastic credit card and which includes a memory implemented as an integrated circuit device, commonly referred to as a "chip", in which information is stored. For this reason such cards are also often known as "chip cards".
The smart card may comprise a subscriber identity module (SIM). Also, In addition to subscriber identity information, such as the subscriber telephone number, and personal identification number (PIN), the smart card may store for example, call charge information (i.e. a charge meter), a telephone number index, or false PIN entries.
SIM cards are currently available in two sizes. The functionality of the SIM is the same for each, it is essentially that the physical dimensions are different. One is a credit card size SIM, the other is a plug-in SIM about 15 mm.times.20 mm.
The rationale behind the different sizes is that the credit card size is perceived as a convenient size for the user from a practical standpoint. However, the credit card size is relatively large, and smaller card sizes are needed as miniaturization continues to drive down the overall size of the terminal (i.e. the radio telephone unit itself). The plug-in SIM is intended to be semi-permanently installed in the cellular telephone.
FIGS. 1a to 1d of the accompanying drawings illustrate an arrangement for securing a SIM card in a mobile telephone, as disclosed in EP 0 679 002. This arrangement enables a credit-card sized SIM card 8 to be attached to a mobile telephone by providing the mechanical frame or casing 1 of the telephone with a pair of grooves 6, into which the SIM card 8 can be slid longitudinally with one end first. On the surface of the mobile telephone facing the SIM card 8 there is a SIM connector 4, with a number of generally flexible connector lugs 5 that make electrical contact with the contact pads on the respective surface of the SIM card 8. The grooves are also used to slide a rechargeable battery unit 9, having corresponding guides 10, into place so that once properly installed, the battery unit 9 essentially covers the SIM card. In the battery unit there is often included a spring that exerts a force against the surface of the mobile telephone or the SIM card 8 while the battery unit 9 is in place, in order to keep the battery unit (and the SIM card) tightly fastened. If the card is inserted wrong edge first, the no SIM card contact pads make contact with the connector lugs 5 of the connector 4.
One problem with the aforementioned arrangement is that it is adapted for use with full size SIM cards, which inhibit the reduction in size of a telephone. Also, the card cannot be readily inserted as it has to be aligned with the pair of grooves 6 before it can be slid longitudinally into position. Moreover, when the battery unit 9 of the mobile telephone is detached from the frame 1 of the mobile telephone, the SIM card tends to slide over the connector lugs 5. Since there is capacitive energy stored in the telephone, the SIM card 8 can be easily damaged while sliding over the connector lugs 5.
FIG. 2 of the accompanying drawings illustrates a known arrangement for securing a plug-in SIM card in a mobile telephone. On one surface of the mobile telephone facing the SIM card 24 there is a SIM connector 27 having connector lugs 26. The arrangement also comprises a hinged SIM card holder 22 with a lock 23 for maintaining the contacts of the SIM card in contact with the connector lugs 26 of the SIM connector 27. The SIM card 24 is inserted in the mobile telephone as follows. Firstly, the SIM card is placed in the holder 22 between the hinged portion 28 and the lock 23. Then the holder is pivoted to the SIM connector and locked by sliding the lock 23 until it connects with a corresponding part on the surface of the mobile telephone facing the SIM card 24. Finally, the SIM card compartment is closed by a cover 25.
The manufacturing process of a mobile telephone comprising such an arrangement is complicated by the number of parts of the hinged mechanism. Also, the arrangement requires a large compartment in the telephone casing. Further, the card 24 cannot be readily inserted as it has to be aligned between the hinged portion 28 and the lock 23 before it can be slid longitudinally into the position in which it needs to be locked. Moreover, the SIM card and compartment have to be adapted so that the card can only be put in the correct way around. Otherwise, incorrect contact between the card and mobile telephone might take place which could damage the card.